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Fri, 30 Oct 2020 01:27:38 -0700 (PDT) Date: Fri, 30 Oct 2020 09:27:19 +0100 From: Jean-Philippe Brucker To: Masami Hiramatsu Subject: Re: [PATCH] arm64: kprobes: Remove redundant kprobe_step_ctx Message-ID: <20201030082719.GA122147@myrica> References: <20201029173440.117174-1-jean-philippe@linaro.org> <160402038829.313559.6664989279479113647.stgit@devnote2> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <160402038829.313559.6664989279479113647.stgit@devnote2> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201030_042741_085573_A6599367 X-CRM114-Status: GOOD ( 25.80 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Oct 30, 2020 at 10:13:08AM +0900, Masami Hiramatsu wrote: > The kprobe_step_ctx (kcb->ss_ctx) has ss_pending and match_addr, but > those are redundant because those can be replaced by KPROBE_HIT_SS and > &cur_kprobe->ainsn.api.insn[1] respectively. > To simplify the code, remove the kprobe_step_ctx. > > Signed-off-by: Masami Hiramatsu Reviewed-by: Jean-Philippe Brucker > --- > arch/arm64/include/asm/kprobes.h | 7 ----- > arch/arm64/kernel/probes/kprobes.c | 53 ++++++++---------------------------- > 2 files changed, 12 insertions(+), 48 deletions(-) > > diff --git a/arch/arm64/include/asm/kprobes.h b/arch/arm64/include/asm/kprobes.h > index 8699ce30f587..5d38ff4a4806 100644 > --- a/arch/arm64/include/asm/kprobes.h > +++ b/arch/arm64/include/asm/kprobes.h > @@ -28,18 +28,11 @@ struct prev_kprobe { > unsigned int status; > }; > > -/* Single step context for kprobe */ > -struct kprobe_step_ctx { > - unsigned long ss_pending; > - unsigned long match_addr; > -}; > - > /* per-cpu kprobe control block */ > struct kprobe_ctlblk { > unsigned int kprobe_status; > unsigned long saved_irqflag; > struct prev_kprobe prev_kprobe; > - struct kprobe_step_ctx ss_ctx; > }; > > void arch_remove_kprobe(struct kprobe *); > diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c > index ec1446ceacc9..3c74fc9e2acf 100644 > --- a/arch/arm64/kernel/probes/kprobes.c > +++ b/arch/arm64/kernel/probes/kprobes.c > @@ -34,7 +34,7 @@ DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; > DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); > > static void __kprobes > -post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *); > +post_kprobe_handler(struct kprobe *, struct kprobe_ctlblk *, struct pt_regs *); > > static int __kprobes patch_text(kprobe_opcode_t *addr, u32 opc1, u32 opc2) > { > @@ -81,7 +81,7 @@ static void __kprobes arch_simulate_insn(struct kprobe *p, struct pt_regs *regs) > p->ainsn.api.handler((u32)p->opcode, (long)p->addr, regs); > > /* single step simulated, now go for post processing */ > - post_kprobe_handler(kcb, regs); > + post_kprobe_handler(p, kcb, regs); > } > > int __kprobes arch_prepare_kprobe(struct kprobe *p) > @@ -184,19 +184,6 @@ static void __kprobes kprobes_restore_local_irqflag(struct kprobe_ctlblk *kcb, > regs->pstate |= kcb->saved_irqflag; > } > > -static void __kprobes > -set_ss_context(struct kprobe_ctlblk *kcb, unsigned long addr) > -{ > - kcb->ss_ctx.ss_pending = true; > - kcb->ss_ctx.match_addr = addr + sizeof(kprobe_opcode_t); > -} > - > -static void __kprobes clear_ss_context(struct kprobe_ctlblk *kcb) > -{ > - kcb->ss_ctx.ss_pending = false; > - kcb->ss_ctx.match_addr = 0; > -} > - > static void __kprobes setup_singlestep(struct kprobe *p, > struct pt_regs *regs, > struct kprobe_ctlblk *kcb, int reenter) > @@ -216,7 +203,6 @@ static void __kprobes setup_singlestep(struct kprobe *p, > /* prepare for single stepping */ > slot = (unsigned long)p->ainsn.api.insn; > > - set_ss_context(kcb, slot); /* mark pending ss */ > kprobes_save_local_irqflag(kcb, regs); > instruction_pointer_set(regs, slot); > } else { > @@ -250,13 +236,8 @@ static int __kprobes reenter_kprobe(struct kprobe *p, > } > > static void __kprobes > -post_kprobe_handler(struct kprobe_ctlblk *kcb, struct pt_regs *regs) > +post_kprobe_handler(struct kprobe *cur, struct kprobe_ctlblk *kcb, struct pt_regs *regs) > { > - struct kprobe *cur = kprobe_running(); > - > - if (!cur) > - return; > - > /* return addr restore if non-branching insn */ > if (cur->ainsn.api.restore != 0) > instruction_pointer_set(regs, cur->ainsn.api.restore); > @@ -371,33 +352,23 @@ static void __kprobes kprobe_handler(struct pt_regs *regs) > */ > } > > -static int __kprobes > -kprobe_ss_hit(struct kprobe_ctlblk *kcb, unsigned long addr) > -{ > - if ((kcb->ss_ctx.ss_pending) > - && (kcb->ss_ctx.match_addr == addr)) { > - clear_ss_context(kcb); /* clear pending ss */ > - return DBG_HOOK_HANDLED; > - } > - /* not ours, kprobes should ignore it */ > - return DBG_HOOK_ERROR; > -} > - > static int __kprobes > kprobe_breakpoint_ss_handler(struct pt_regs *regs, unsigned int esr) > { > struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); > - int retval; > - > - /* return error if this is not our step */ > - retval = kprobe_ss_hit(kcb, instruction_pointer(regs)); > + unsigned long addr = instruction_pointer(regs); > + struct kprobe *cur = kprobe_running(); > > - if (retval == DBG_HOOK_HANDLED) { > + if (cur && (kcb->kprobe_status == KPROBE_HIT_SS) > + && ((unsigned long)&cur->ainsn.api.insn[1] == addr)) { > kprobes_restore_local_irqflag(kcb, regs); > - post_kprobe_handler(kcb, regs); > + post_kprobe_handler(cur, kcb, regs); > + > + return DBG_HOOK_HANDLED; > } > > - return retval; > + /* not ours, kprobes should ignore it */ > + return DBG_HOOK_ERROR; > } > > static struct break_hook kprobes_break_ss_hook = { > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel